The story of hexavalent chromium, a carcinogen, in drinking water is not over, even though Erin Brockovich's legal victory was vaunted in a film 13 years ago. Groundwater near Hinkley, Calif., is still polluted. The story of how industry clout has kept EPA delaying regulation of chromium in drinking water is a tale of the chemical industry's ability to manipulate regulation by sowing doubt. But recent highly dramatized stories on chrome-6 in drinking water may not have helped much, to the extent that they downplayed natural background levels, the importance of dose, and the statistical problems in identifying cancer clusters. The whole saga raises key issues about public relations, lobbying, regulatory politics, the legal system, environmental journalism, and the protection of public health.

"The hit 2000 film Erin Brockovich, which tells the story of how a novice legal clerk holds a huge corporation liable for contaminating a town's drinking water with the carcinogenic chemical hexavalent chromium, or chromium (VI), ends in justice for those harmed. But as it turns out, Hinkley, California, the real-life town featured in the movie, is still contaminated.""Not only that, but when the U.S. Environmental Protection Agency (EPA) was about to announce its findings in 2011, citing 'clear evidence' that the chemical can cause cancer (evidence that has been mounting since the 1950s), the chemical industry lobbying giant, the American Chemistry Council (ACC), urged the EPA to delay -- and succeeded. Issuing those findings would have been a first step towards generating tougher rules to protect clean water. In February 2012, the EPA quietly announced on its website that the findings wouldn't be released for at least another four years.

How is it possible for the chemical industry to wield so much power over the agency that is tasked to regulate it? A PBS NewsHour series released this month in cooperation with the non-profit investigative news organization Center for Public Integrity (CPI) called "Toxic Clout" explores how the industry's actions create uncertainty and delay, which, the series argues, threatens public health."